In AIDS patients, the incidence of Pneumocystis carinii pneumonia (PCP) is increasing primarily due to the fact that the actual numbers of AIDS patients is increasing dramatically in the United States. Because of this, there is a need to develop faster and less time-consuming diagnostic techniques than the currently accepted technique of bronchoscopy. The purpose of this study is to evaluate the sensitivity of sputum induction as a non-invasive diagnostic procedure in patients with suspected PCP. Patients undergo sputum induction using an ultrasonic nebulizer with a 3% saline solution. Specimens are processed by the microbiology department and are stained conventionally with toluidine blue 0 to look for PCP. In addition an experimental human monoclonal immunoflourescent staining technique to determine the presence of pneumocystis in sputum is also being investigated. Patients with PCP documented by sputum induction have therapy instituted, however, those with "negative" sputums undergo bronchoscopy with bronchoalveolar lavage and transbronchial biopsy in order to determine an etiology for their pulmonary dysfunction and also to establish the sensitivity of sputum induction for the diagnosis of PCP. Preliminary data indicate an 80% sensitivity for the diagnosis of PCP by sputum induction. Thus, this technique may reduce the time, cost, and morbidity associated with establishing the diagnosis of PCP.